The following are brief notes on how to use the radvis radiosity
visualisation program. Hopefully at some stage they will be replaced by
highly detailed notes with lots of demonstration images. In the meantime,
if you have any questions/suggestions, please email ajw+rv@cs.cmu.edu.

This shows the current scene. The scene can be manipulated by clicking
on it with the mouse as follows:

Left Mouse Button:

Rotate scene about its centre

Left Mouse Button + Shift:

Zoom in and out

Middle Mouse Button:

Translate the scene in x and y

Middle Mouse Button + Shift:

Translate in z

Right Mouse Button:

Pick a receiving patch. The patch will be highlighted yellow, along
with the corresponding row of the matrix.

Right Mouse Button + Shift:

Pick an emitting patch. The patch will be highlighted green along with
the corresponding column of the matrix.

When using the right-mouse to select a patch, the initial click will select
one of the leaf nodes in the mesh. For the hierarchical meshes used in
wavelet radiosity and progressive radiosity with substructuring, elements
at higher levels in the mesh can be selected by keeping the mouse down,
and dragging away from the initial click point. The futher you drag, the
higher up in the hierarchy will the patch be selected, until eventually
the root patch is reached.

Matrix radiosity, with the matrix equation solved by the successive overrelaxation
technique.

Conjugate-Gradient

Matrix radiosity, with the matrix solved by the conjugate gradient technique.

Progressive

Progressive radiosity: radiosity is shot from light sources, rather than
gathered into each patch in turn.

Prog./Substructuring

Progressive radiosity with a bi-level mesh. Radiosity is shot using a relatively
coarse mesh, and received over a finer one. The receiving mesh can be subdivided
in areas that have a high radiosity gradient. (E.g., shadow boundaries.)

Wavelet

Wavelet radiosity, a la Gortler et. al. In this case the mesh is multi-level,
and different types of basis functions can be used over the mesh. If the
Haar (constant) basis is used, this reduces to Hierarchical radiosity.

Analytical

For scenes where there is no inter-reflection(!), this will find an analytical
solution to the radiosity equation.

Basis

Selects the type of basis used for wavelet radiosity. The currently supported
bases are Haar, the flatlets F2 and F3, and the multiwavelets M2 and M3.

Scene

This popup menu either selects one of the built-in scenes to use, or allows
you to load an external scene file.

Controls the density of the element mesh in the progressive + substructuring
method. For this method, Patch Subdivisions controls the density of the
mesh used for shooting radiosity, and the Element Subdivisions setting
controls the density of the mesh used for receiving that radiosity.

Termination Error

The error level at which to terminate the simulation.

Refinement Level

For the progressive + substructuring method this determines the threshold
at which to subdivide a element of the mesh, and for the wavelet methods,
it sets a limit on the form-factor error. (The smaller the number, the
more the mesh is subdivided to reduce this error.)

Offset each mesh element according to how bright it is. (Makes it easier
to see the distribution of radiosity.)

Patch's View

When this is on and wavelet radiosity is selected, the scene is displayed
relative to the currently- selected patch. Patches that contribute radiosity
directly to that patch are coloured normally; patches that contribute radiosity
to its children are drawn wireframe, and patches that contribute radiosity
to its ancestors are drawn outlined in red.

Animate

Animate the radiosity simulation by highlighting relevant patches.

Show Rays

Display all rays traced for visibility determination.

Show Links

Show which patches are being linked together. (Wavelet radiosity only.)

Graded Mesh

For the hierarchical meshes, ensure that any adjoining mesh elements differ
by at most one level in the quadtree.

Anchored Mesh

Use 'anchoring' to avoid problems with T-vertices, such as discontinuities
in shading. This requires that the mesh is graded.

This shows a list of the avars embedded in the scene, and a slider for
adjusting them. Avars can only be changed when a radiosity method isn't
running. Depending on the scene, avars can be used to vary the emissivity
or reflectivity of certain objects, or their location or orientation.

Selects among various (somewhat obscure) variations of form-factor calculation.
'None' uses point-to-point form factors, 'PF switch' uses the area-to-point
form factor as a correction near singularities, and the remaining options
select various combinations of area-to-point samples.

dF Error

Threshold dictating when to switch to the area-to-point approximation when
using the 'PF switch' method.

Visibility

The type of visibility estimation to use: no rays, one ray between each
pair of patches, sixteen from the centre of the receiver and distributed
evenly over the source, and sixteen distributed evenly over both source
and receiver.

Vis. In Quadrature

If this is on, visibility is sampled within the quadrature method for higher
order wavelets, rather than using the fractional visibility to scale the
results of quadrature.

Recalc Jitter

If this is on, a different jitter pattern is used each time the visibility
between two patches is estimated.